Research On High Gain Terahertz Antenna

With the rapid development of science and technology,the existing frequency band resource have become increasingly scarce and tend to be saturated,it can not meet the needs of the development of communication technology.Therefore,people have shifted their sights to the untapped Terahertz band.With the depth study of the terahertz band,antenna has a higher technical requirements and attracts more attentions,as an indispensable tool in wireless communications.However,the terahertz band has high operating frequency,small wavelength,large loss of electromagnetic waves immaturity of the front-end detection technology in the THz communication system,which make the gain and directionality of the antenna in the THz band have a strict requirement.Since the conventional planar antenna band exists a serious surface wave effect,the commonly used microstrip antenna can not be directly used in the terahertz band.Hence,it is necessaray to change the antenna structure for eliminating this defect.Thus,the transmitarray antenna is selected as the main research object of this thesis.The lens antenna and the planar transmitarray antenna are proposed at the terahertz band in this thesis.The main contents can be summarized as following:1.The lens antenna has been systematically studied and designed.The lens antenna with E-shaped bow-tie microstrip patch is designed.Firstly,the structure of the radiator is optimized so that relative bandwidth is up to 38%,thus obtaining the ultra-wideband performance.Then,the optimized radiator will be integrated into the lens.The parameters of the lens structure are properly studied,and the antenna is obtained the high gain to meet the design requirements through optimize structure.2.The non diffracting of terahertz transmission antennas is studied.On the basis of the lens antenna study,the beam of the horn antenna is collimated by the lens,and will achieve the Gaussian beam with the obvious waist.Then,the collimated Gaussian beam with the obvious waist passed through the pyramid,and will form an approximate non-diffraction beam.The beam has the Bessel function form and realizes a long-distance transmission with non-diffraction.3.The planar transmitarray antenna is designed.Firstly,a double-layer ring slot element with frequency selective structure is proposed.The unit transmited the electromagnetic wave by the feed source and the phase of each element is adjusted by phase correction through changing the size of each unit.The structural parameters of the element are optimized.The optimized unit and the transmission phase range is used to design a planar transmitarray antenna operating at 100 GHz.The gain of the array antenna is improved by 6d B.Then,a planar reflectarray antenna with a circular microstrip patch is designed.It is found that the gain of the reflectarray antenna is lower than the transmitarray antenna when they are compared,indicating that the reflectarray antenna will cause a loss of energy due to the existing feed blockage effect.